1. Field of the Invention
This invention relates generally to a multi-layer sponge and, more particularly, to a multilayer sponge providing increased surface conforming capabilities while maintaining preferred lathering, cleaning and scrubbing capabilities.
2. Description of Related Art
It is generally known to combine multiple layers of sponge materials, including multi-layer sponges where the exposed surface of at least one layer is used for aggressively scrubbing or scouring a working article and the exposed surface of another layer is used for less aggressive cleaning operations. Combinations of porosities, densities, and compressibilities are known to be used in these sponges. Generally, the scrubbing layer is formed with bristles or strands of fibers that are woven together or otherwise attached to a pad as in U.S. Pat. Nos. 3,428,405, 4,820,579, and 5,814,388. Alternatively, the scrubber layer may be formed from a stiff foam material that is cut into a convoluted shape as in U.S. Pat. No. 3,857,133. The cleaning layer can be used for wiping, buffing or polishing and is generally formed from an open-cell foam material, usually a polyol-based polyurethane. For the cleaning layer, it is well known to use foams that are fully or partially reticulated, and the preferred foam is generally a polyester-based polyurethane due to its increased strength and durability over a polyether-based polyurethane. The porosity of the cleaning layer is generally greater than the scrubbing layer porosity, and the prior art generally teaches decreasing porosity as the thickness of the cleaning layer increases, as in U.S. Pat. No. 3,377,643.
It is further known for some sponges to have three layers. However, none of these three-layer sponges have an internal layer that is more compressible than one external scrubbing layer and another external cleaning layer. Additionally, none of these three-layer sponges has a groove at a perimeter of the sponge to permit increased compression of the external layers at a region around the groove. Some of the known three layer sponges combine a cleanser into the sponge itself. A sponge may encase a cleanser between two layers that have identical compressibility as in U.S. Pat. No. 4,820,579. Alternatively, a layer or layers may be impregnated with a cleanser as in U.S. Pat. Nos. 3,396,419, 3,949,137, and 4,866,806. According to these known sponges, the internal layer is either too thick relative to the external layers for it to have increased compressibility or one of the external surfaces is constructed of a material that does not function as a cleaning layer or a scrubbing layer. For those three-layer sponges that do not combine a cleanser into the sponge, the internal layer is generally stiffer than the external layers, as in U.S. Pat. No. 5,640,737. In other sponges, the third layer does not affect the compressibility of the sponge, as in U.S. Pat. No. 3,857,133.
The hardness of the cleaning and scrubbing layers must be sufficient to function for their respective operations, and the requisite hardness for cleaning and scrubbing operations limits the ability of the sponge to conform to working surfaces. Some sponges have been designed with protuberances to allow better conformance of the sponge surfaces to the working surface. The protuberances may be on the side of the sponge as in U.S. Pat. Nos. 5,836,034 and 4,866,806, or the protuberances may be on the surface of the sponge as in U.S. Pat. Nos. 4,111,666 and 3,611,468. However, the prior art does not suggest providing a groove in an internal layer between the scrubbing layer and the cleaning layer to permit increased conformance of the sponge around the region of the groove. Additionally, multi-layer sponges fail to suggest using an internal layer that is more compressible than the scrubbing layer and the cleaning layer. In U.S. Pat. No. 5,640,737, an internal layer has greater porosity than the external layers to permit the absorption of more water, but the invention particularly teaches using external layers that are softer than the more abrasive internal layer; this internal layer provides additional firmness to the sponge, not increased conformability.
It is in view of the above problems that the present invention was developed. Among the objects and features of the present invention is a multi-layer combination sponge providing an intermediate layer between a scrubbing layer and a cleaning layer; the intermediate layer having lesser hardness than the cleaning and scrubbing layers.
A second object of the present invention is to provide such a combination sponge that permits the scrubbing layer and the cleaning layer to better conform to a working surface.
A third object of the present invention is to provide such a combination sponge that conforms to a user""s grasp on one surface, transitions its shape through an intermediate layer, and conforms to a working surface on an opposite surface.
In one aspect of the present invention, a combination sponge includes a scrubbing layer, an intermediate layer, and a cleaning layer. The scrubbing and cleaning layers are laminated to opposite sides of the intermediate layer. The intermediate layer is more compressible than the scrubbing layer and the cleaning layer.
In a second aspect of the present invention, a combination sponge includes a scrubbing layer, an intermediate layer, a cleaning layer, and a groove around the perimeter of the sponge. The scrubbing and cleaning layers are laminated to opposite sides of the intermediate layer. The intermediate layer is more compressible than the scrubbing layer and the cleaning layer, and the groove permits additional compression of the sponge around the region of the groove.
Further features and advantages of the present invention, as well as the structure and operation of various embodiments of the present invention, are described in detail below with reference to the accompanying drawings.